Electric connection



March 27, 1928.

C. L. M. RAVUT ELECTRIC CONNECTION Filed July 8. 1924 2 Sheets-Sheet 1C. L. M. RAVUT ELECTRIC CONNECTION Filed Jul v 8, 1924 2 Sheets-Sheet 2k-- I 0 I Kr munication circuits which are independent v with the doublepair grouping, while on the.

other hand the second class clrcuits Wlll be Patented Mar. 2?, 1928..

warren s rates marina a CAMILLE Louis MARIE we, ermine- RANCE, AssIGnon.mosoo'ln'rn INDUS- TRIELLE DES rnLnrnonns (CONSTRUCTIONS nLnc'rRIQUEs,oeou'ronouo, CABLES),

OF PARIS, FRANCE.

ELECTRIC connncrron.

Application filed July 8, 1924, Serial No. 724,870, andjin FranceFebruary 28, 1924.

. The present invention relates to a system of electric connections,chiefly apphcable to long-distance telephony, in whlch the wires likecommunication, and with the -.use of a triple three-wire circuit we areenabled to provide a combination or phantom threewire circuit comprisingtwo additional comof each other and independent of the communicationcircuitsoflered by each of the component three-wire physical circuits.In

this manner, the wires are more efficiently employed than in the knownsystem. Taking as an example a group of72 conductors-to facilitate thecalculations-,-if the conductors are disposed in double pairs they Iwill constitute 18 double pairs and will hence altord 36 physicalcommunicatlon circuits of the usual type or of the first class,

as well as 18 phantom communication circuits, or circuits of the secondc-lassb But if the said conductors are disposed as triple three-wirecircuits, they will form8' triple three-wire circuits, i. e. 3 8=21physical three-wire circuits providing 2 2l=48 communication lines ofthe first class, while the phantom circuits will afford 2 8=16coinmunication circuits of the sec'ondclass.

By my arrangement of the conductors in triple three-wire sets, we arethus enabled to provide 4836=12 effective circuits of the first class inaddition to what is obtained diminished by 1816=2 circuits. However thetotal gain will be (&8+16) (36+ mented by about 20 percent by my saidarrangement. 1

' The characteristics of the telephone communications of the first classare identical within the limits of uniformity of the electric constantsof the several conductors of *the setbut differ from the characteristicsofthe conductors of the second class.

The following description, together with the appended drawings which aregiven by way of example, sets forth my saidinv ention. a Figs 1 and 2show respectivelyin cross section and in elevation the three conductorsV forming a three-wire set.

V Fig; 3 represents aline circuit. Fig. 4: is a diagram of a completeinstallation. V V

Fig. 5 is a diagram of the arrangement of circuits atthe ends of theline.

Fig. 6 shows a line employing a triple three-wire set.

In the system according to the present in vention, the wires aredisposed in three-wire sets and in triple three-wire sets. understoodthat the three wires of a' set-have an identicalconstruction andinsulation, and

they are moreover formed 'into a cable strand of the three-wire'type,the three in- It is' sulated conductors being juxtaposed and twistedin'helical form around a common geometric axis, in such manner that thecentres of the three conductors upon a plane perpendicular to the cableaxis shall repre sent the three vertices of an equilateral triangle.Figs. 1 and a. WVheu this arrange ment is to be tripled, each of theconstituent three-wire sets is considered as a single conrluctor, andthe preceding remarks will be equally applicable. By the useof adequatearrangements at the ends of the line, in accordance with certainconditions to be hereinafter setfltorth, the independent circuits canbe'properly separated. i

-The present invention, although 7 chiefly applicable to telephonecables, is independ"- ent of the nature of the conductors and theinsulation, and relates to sets of overhead line wires as well as'toconductors in the form of cables, and the conditions can be transposedin an immediate manner.

Considering in the first place a single set of three conductors, thethree wires are identical and are geometrically situated in conditionsof symmetry such that their relative position in pairs is always thesame.

Let R be the resistance of each Wire per unit length.

L the coetficient of self-induction of each wire per unit length.

C the capacity of each wire per unit length relative to the sheathinspectively between a wire and the set, and between one Wire and another;per unit length. '0 e 0 the potentialof each wire at the distance atfrom the initial or Zero point.

71, '5 i the current in each wire at the distance as from the zeropoint. p For the distance a: from the Zero point,

the equations of propagation will be:v

M the coefficient of mutuaTinduction of (1) -g =Mi R+L)i +1\/I i any twowires oi the set, per unit length. m t r at C the capacity of any twowires relative L to each other, per unit of length. 5:13 575 at G and Gthe losses per unit length reand e +2e co-mm la{mega-(meg 5' 6 2 ;=-(e+cv (G +2G)+(C +2C)%IQJ G+C QJ a a a a (o tc ael-o )a+l c +ze o wm j If wedesi nate by oz and 1x the two imagi- 6 6 nary cube Toots of unity, andby x )I A i x =p. =q. four numerical coelfi- 3 5 cients which can betemporarily given any x :[3G+G0+ G o) g j i desired value, and aresubjected solely to the condition a ag A2/1#O, or what is the same, (3)pq#O We can at once substitute for the six equations (1) and (2) thethree pairs of equations:

defined by the equations The equations (4) characterize the propagationof the potential 1) and the current 1 2 along a line consisting of twowlres of the three-wire set in series, the third wire being separate.The equations (5) characterize the propagation of the potential 0, andthe current t, alongan identical line. These The equivalence of theequations ('1) and (2) on the one hand and of the three pairs ofequations (4) (5) (6) on the other hand, shows that the real propagationof potentials and currents 12 ,42 0 2' i 46 in the three Wires of theset is equivalent to the superposition of three virtual propagations ofan independent nature which have been above specified.

Since the imaginary cube roots of unity have introduced the symbol 1, itwill be henceforth supposed that the considerations will bear uponpotentials and currents which are functions of the time and have theform A. e it being understood that finally, by retaining only the realportions, for instance,

and not departing from linear relations be-' the, three wires of theset, by two pairs of terminals A A 1 A A' to two independent sources ofcurrent, and by the last terminal A to a third source of current whoseother pole is grounded; this disposition has the following particularfeatures:

1. The source of current connected at A A 1 only intervenes in the valueof the line potentials and currents by modifying the value of thepotential 22, and the current 7/ A A 2 acts only upon the combinations2),, and i of the line potentials and currents.

3. The source of current connected at A acts only upon the combinationsv +v +12 and Since the nature of v i 1),, i will depend upon thearbitrary values X, p, q, a great variety of dispositions can beemployed, according to the values which are selected for these fourfactors, it being however stipulated that 1) must be other than g. Itcan be readily demonstrated that p+q should have a zero-value. We niaylikewise determine the conditions to be complied with by an arrangementcomprising three outgoing terminals B B B and two pairs of incomingterminals A A A A; with an additional incoming terminal A in order topossess the above mentioned properties. We will indicate the requiredconditions and show how these are obtained. In this case it isunderstood that if a disposition comprising the above-mentioned incomingand outgoing terminals complies with the conditions to be hereinafterset forth' which can be shown by experimentthe values A a p q (real orimaginary) will exist, by means of which we may set out potentials andcurrents 12, i 0,13,, in accordance'with the formulae (7), in suchmanner that the action will takeplace as if the source of currentconnected at A A 1 acted directly upon the potential 1), and thecurrent; i the source connected at A A upon the potential 12,,

and the currenti and the source con- 22 +12 nected at A upon thepotential and the current "i +i +i I If we connect two identicalarrangements to the two ends of the line (Fig. 4), the

2. The source of current connected atdistributed in three groups.

lent, and will act at'the receiving end upon did not exist. A likeaction will take place between A A; and C U and between A and C We thusobtain on. the threewire set three entirely separate communications. i

Since the potentials and currents a g i,

1 r or v, 5 t, are each propagated along a line similar to what would beconstituted by two wires of the three-wire se t-thethird wire beingisolated it will be observed that whatever may be the values of A ,u. pq, the sole fact that the terminal circuits comply with the conditionsto be hereinafter set forth implies the obtainment of three independentcommunications.

We will briefly indicate the method of attaining the condition 1) q =0,and the conditions stipulated for the terminal circuits.

Let 2'2 22 22 (Fig. 4) be the potentials of the three terminals B1 B2B516 m the potential differences applied between the terminals A and A 1and between the terminals A A and u the potential applied to theterminal '65 C C for instance, as if the other receivers,

A j jg j are the currents from the terminal 1 potentials. 7

We will take as a starting point the general theory indicated by M. IC.Ravut in the Revue Gnrale delElectricite, vol. XIV, N0. 17. This theoryshows that in a circulation network having 8 poles or terminalsconnected by connecting currents with out-,

arrangement which maintain the various side sources of supply, if thesaid-poles constitute n groups in such manner that in each group theconnecting currents have a simple relation such as a linear relation,there will exist a function, quadratic, homogeneous and of the seconddegree, H, of the connectingcurrents of the other s-n poles,"su ch thatthehalf-derivative of this function H relative to one of these s-nconnecting currents shall be equal to the difference of potentialbetween the corresponding pole and areference pole chosen fromeach ofthe it groups.

The terminal disposition here considered is in fact, a network having 8'terminals 1. The group B B B whereof ence pole is the pole A thecurrentsbeing poles being a reference pole, the currents being 1' and j in suchmanner that .3. The group A A one of these two poles being a referencepole, thecurrents being 3: and -j in such 'manner that the refer- 4 i iand j in such manner that i +i i i l 2. The group A A one of these two aquadratic function. of five currents i i i 3 jg, for instance. I

The equation 12 (7):; 04 22 E (v -u aha-a a (22 u permits the formationof the linear functions (7) 12 i v, '5 depending upon the second membersof the first three equations (9).

We then substitute in the first three equa c d Cgdg and we also findwhence: p q 0, these latter equations be ing compatible with theequations (10).

If a given arrangement complies with the conditions (10) we find for e i7), i the Values 7),, /1 ((1 11 (Z202 (lg U n I i' l z' z a s) and nbeing coefiicients of proportionality which are not defined, the .c andthe d being the coeflicients of the characteristic H of the arrangement.

By reason of the first conditions (10), e t 1) i will in fact have theform indicated in the equations (7), and the problem is solved whereinwe act individually by the 8 sources upon potentials and currentspropagated over the three-wire set according to the equations (4) (5)and (6).

The coefficients a; b, c, d of the function H (which are homogeneouswith impedances) may be calculated according to the diagram of circuits;they may also be measured upon an arrangement which is constituted inorder toascertain whether the conditions (10) have been properly carriedout.

We may provide aphysical expression of the conditions (10) by returningto the equations (9). We can readily verify whether these conditions(10) are equivalent to the following:

1. Condition b =O.The two outer circuits A A and A A shouldbeindependent of each other after the manner of the two diagonals of abalanced Wheatstone bridge, when the outer terminals B B B are isolated.

2. Conditions c +c +c =O and d +d d =O.lf a potential difference it isused between the terminals A A the sum of the potential differencesbetween each outer terminal B 1 2 B and the supplementary terminal Ashould be null, and irrespectively of the value of the externalimpedance inserted between the terminals A and A The same is true if inthe preceding case we use A A g instead of A A or A A instead of A A 3.Conditions a (r (1 (r (L33 (1 If We isolate the four terminals A Ai A Ag and use between each terminal B B B and the terminal A potentialdifferences whose sum is zero (e. g. three potential differences on theV three-phase system) the current traversing the supplementary terminalA should be null.

a m 21 21, 2 2 e 0 d 0 d c 11 Since the terminals A A A A and B B areisolated a current i is caused to enter at the terminal B and to leaveat the terminal A It produces between A and A a potential difference ubetween A and A g a potential difference a and between B and- ]3 apotential difference v t We deter mine the fourth proportional factorif) for these three potential differences. If wenow treat the threeterminals B B B by circular permutation, while maintaining a constantvalue for the current i, this fourth factor should remain constant inthe three measurements. In this case as well as in the rest of myexposition, the potentials are considered in the vector form 22=Ve 6being the phase of v with respect to an initial point which is of anarbitrary nature.

5. Condition 0 cZ,+c c +d d =0.This condition is satisfied when theconditions specified in the preceding paragraph are 4. Conditionssatisfied. The independence of the communications exchanged between A A,and C C on the other hand, between A A and C C on the other hand, andfurther, between A and C will prevail irrespectively of the variationsin the as, bs, cs and ds relative to the pulsation, at least for allpulsations for which the conditions are complied with; but in this casethe potentials and currents 22 i and 2),, i, which are propagatedindividually over the three-wire set are differently compounded,according to the frequencies, with the potentials and currents of theFor this reason one of the communications will be entirely confused andunintelligible upon the Whole length of the line connecting the endoutfits, although it will be veryvclear and without confusion betweenthe corresponding outfits; 'The whole action will take place as if thevarious pulsations concerned in the telephone comground. municationbecame separated in the connecting arrangement at the transmitting endand were separately distributed, each in its own manner, upon the threewires of the set between the outfits at each end,then coming together inan accurate manner in the connecting arrangement at the receivingendexcept for any distortion which may be due to the length of thethree-Wire line. V

cal connectingthree wires of the set.

As an example of a practl arrangement, we will describe the a ment whichis illustrated in Fig. 5. transformer in which the middle part of thesecondary is accessible, this being analogous to a coil of thetelegraphic type which is in current use for two-Wire telephonecircuits; T is a transformer of. the usual type with T T 3 T are three.similar ch is provided with two windings.

transformers each of whi two windings.

The primary W1 T1 is a a a (1 rrangendings of'thetransformers T T' T aredisposed on the star system about a central point which is connected tothe external incoming terminal A primary windings are each connected toone The said of the three outgoing terminals 13, B B to which areconnected the ends of the three wires of the telephone line. r

The secondary windings of the transformers T T .T are also disposed onthe star system about an isolated central point. Further, thesecondaries Nos. 1 and 2, corresponding to the outgoing terminals B andB are each connected tov one end of the secondary of the transformer TThe middle point of the secondary of T is connected to the outgoing endof the secondary No. 3 of the group T T 3 T corresponding to theterminal B through the secondary of the transformer T The primary of Tis connected to the two incoming terminals A A and the primary of T tothe two incoming terminals A A The sources of current are disposed asfollows: (1) between A and A,, (2) betweenA and A (3) between A -and,

The following designations are employed: fZT the impedance 'oftheprimary circuit 0 I fgfZ' the total impedance of the secondary O I y ZMthe mutual induction between the primary of T .and the entire secondary.

M the mutual induction between the two halves of the secondary of T Y Zthe impedance of the prirnary of T Z 'the impedance of thev secondary ofT M the mutual induction between the two windings of T J Z the impedanceof theprimary of T T or T Z the impedance T3, T;;' 01 TH3. i l

' M the mutual induction between the two windings of T T or T If weemploy Kirchoffs equations for this system, and if we seelrforithecoeliicients a b c d of the characteristic-function H, we will findthe followingequations by an easy calculation. a 1

of the secondary of The arrangement thus verifies the condi so that thecompounding of 72 and v with tions (1 O).

2),, assume the simple forms In this particular case, 1)), and v v2 v-will not vary with the pulsation. The said arrangement verifies theconditions (10) irrespectively of. the pulsation 19g w, and it can thusbe employed both for telephony and telegraphy. The precedingconsiderations will now be 1applied to the case of a triple three-wireinc. 7

1. We made use of three triple circuits of the type which has been aboveconsidered, these resembling each other as closely as possible.

2. The three triple circuits are also wound together in a cable, eachbeing treated as a separate conductor of a three-wire circuit.

In these conditions We may make the following suppositions:

1. The resistance per unit length of any one of the nine wires of thethree triple circuits is the same, this being represented by R. V

2. The self-induction of eachwire per unit length is also the same, thisbeing represented by L. V 3. The mutual induction of the wires of anygiven three-wire set, taken in pairs, is the same (represented by -M)irrespectivoly of the three-wire set containing the same.

4. -The mutual induction of any two wires, one pertainingto a giventhree-wire set and the second to another three-wire set, is the same (M5. The capacity of a pair of wires of a given three-wire set is the same(C) irrespectively of the three-wire set containing the said wires; thesame is true for the conductance representing the losses (G).

6. The capacity of a pair of Wires whereof one pertains to a giventhreewire set and the second to another three-wire set is the same ((3')the same is true for the value of element of the length and the effectof the ohmic resistance as well as the electromiotive forces ofinduction, and in like manner for each wire, the equation evaluating theleakage current which leaves the conductors at each point, taking dueaccount of the capacities and losses as well as the distribution ofpotential in the plane perpendicular to the centre line of the threetriple circuits.

We will specify for each three-wire set the abovementioned potentialsand currents e, i, 2),, i,,; in this case, the values of v 2),, andrelative to a three-wire circuit comprise only the currents pertainingto this same circuit, so that all that has been stated for one three- 1wire set concerning the propagations of v, i

and of 2),, 11,, will hold good. We will further specify 12 +v +v foreach three-wire set,

and it is found that the equations giving (v +v +c for the three triplecircuits do not contain the currents of the nine Wires in question,except by the combination i +i employed for each three-wire set. We thuspostulate c +v +e =e for the first threewire set, 1/ for the second set,and 0' for the third set. In like manner, we have i +i +i =t or i or ifor the three sets respectively; between the values of 1; and 'L, theequations have exactly the same form as the initial equations (1), andonly the values of the coefiieients have changed.

For this reason we may consider the three additional incoming poles A AA of the arrangementsserving to connect each threewire set of the triplecombination as forming the end of one of the wires of the phantomthree-Wire circuit. In like manner at the other end, as concerns the.additionaloutgoing poles C C C the same conditions prevail. So that allthat has been specified for the three-Wire circuit alone will nowprevail for the phantom three-wire circuit, and the conditions (10) willapply to the end connecting arrangements for the phantom threewirecircuit. But the optimum specification, i. e. the conditions to becomplied with by the constants of the line will not be the same for theend connectingarrangements pertaining to the phantom three wire set asfor the arrangements used with the physical three-wire sets.

With reference to the above-mentioned form of construction, Fig. 6 showsthe end 160 connecting arrangements for a triple threewire set whosephantom three-wire circuit is utilized. The independent communicationsare as follows:

First three-wire set: V I A f 1 71th 011 0 1 A2 'A g XVl'lih C21 "21Second three-wire set:

WI 2 k 2 I 2 1 '1 with 1 1 1 Phantom .circuits A}! 1 Wlbll C1: 1;

There will. also be an independent com- "Vitrh 02 3 2 'municationbetweenA and C relatin to potential in each wire in the specification of130- 1. A system of long distance telephonic or 'other electriccommunication comprising three insulated wires having an identicalconstruction'and insulation, juxtaposed and twisted in helical formaround a common geometric axis, in such manner that the centers of thethree conductors upon a plane perpendicular to the twisting axis occupythe three vertices of an equilateral triangle, thus forming whatiscalled a three-wire set, another three-wire set analogous to the firstone, a third three-wire set analogous to the others, the common windingof the three three-wire sets being juxtaposed and twisted in helicalform around a common geometric axis in such manner that the traces ofthe axes of the three three-wire sets upon a plane perpendicular to thecommon twisting axis occupy the three vertices of an equilateraltriangle, three transformers at each end of each three-wire set, twoindependent sources of current, a transformer connected to the.

two poles of the first independent source of current, the primaries ofthe three first transformers being connected respectively with the wiresof the three-wire set and disposed on the star system about a centralpoint connected to a special wire, the secondaries of the three firsttransformers being disposed on the star system about an in sulatedpoint, said secondaries being connected respectively with the ends andthe middle point of the secondary of the fourth transformer and theseries intercalationof the secondary of the second independent sourceupon the connecting wire ending at the middle point of the transformerwhich is connected to the two terminals of the first independent sourceof current, the application to the three special wires provided each ina three-Wire set of a terminal arrangement similar to those applied toeach three-wire set. v

2. A system of electrical communication such as a long distancetelephone system comprising the following instrumentalitles:

three conducting units or sets of three wires each twisted in a helicalform around a common geometric axis, sothat the centers of the threeconductors in each set in anyplane perpendicular to the common axis areat the vertices of an equi-lateral triangle, all of the three unit setsbeing likewise twisted around a common geometric axis so that in anyplanes perpendicular to said axis the geometric centers of the threeseveral units will also form an equi-lateral triangle; threetransformers at each end of each three-wire set or unit, and twoindependent vsignaling circuits; one terminal .of the primary of each ofsaid transformers being connected to one of the wires of thethree-wireset or unit, and the other terminals of said primaries beingconnected together and to a special neutral conductor; the secondariesof said three transformers being connected ina star connection withoutany neutral conductor; a fourth and a fifth transformer, the primariesthereof being connected to said independent transformer having oneterminal connected to the central point of the secondary of the fourthtransformer and its other terminal connected to the secondary of theremaining one of the first three transformers; the three neutralwiresfrom the three unit sets being conducted to a fourth transformer setarranged in the same manner in every particularas the transformer setsfor the individual units, and also connected with two independentsignaling circuits; nine individual wire conductors function first ingroups of three; each group ofthree serving two circuits; and then thethree groups of three function by means of their neutral wires as unitsforming an additional triplet set, and serve two additional signalingcircuits.

In testimony whereof I have signed this specification;

cAMrLLE LOUIS Mann: RAVU'I.

whereby

